| 摘要 |
PURPOSE:To prevent the entire part of the display of the dot type display device from appearing bright or dark by a difference in lighting rate. CONSTITUTION:The corresponding relations between the lighting rates and the total current quantity of the display are previously stored into a ROM 5. A CPU 4 calculates the lighting rate prior to display output, obtains the data on the total current quantity by referring to the ROM 5 and gives on/off information for the display to an I/O port. The CPU simultaneously gives this data to a latch circuit 3. A D/A converter 2 converts the data of the latch circuit 3 to an analog control voltage and gives the data to a transistor(TR) 1 for current control. The TR 1 controls the total current quantity of an LED for display according to the control voltage.
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